Ben Simo explains his view on Best practices related to the first two principles of the Context-driven school of testing and makes a fantastic conclusion:
No process should replace human intelligence. Let process guide you when it applies. Don’t let a process make decisions for you.
Seek out continuous improvement. Don’t let process become a rut.
Process is best used as a map; not as an auto-pilot.
Matt Heusser came up with some thoughts regarding failing Agile teams. Indeed some time ago Alistair Cockburn already discussed this topic in more detail. I found both quite worth reading.